Fallopia convolvulus
Fallopia scandens
black bindweed, climbing bindweed, climbing knotweed, Eurasian black bindweed, ivy bindweed
climbing bindweed, climbing false-buckwheat
ocrea persistent or deciduous, tan or greenish brown, cylindric, 2–4 mm, margins oblique, face not fringed with reflexed hairs and slender bristles at base, otherwise glabrous or scabrid;
petiole 0.5–5 cm, puberulent in lines;
blade cordate-ovate, cordate-hastate, or sagittate, 2–6(–15) × 2–5(–10) cm, base cordate, margins wavy, scabrid, apex acuminate, abaxial face usually mealy and, rarely, minutely dotted, not glaucous, adaxial face glabrous.
ocrea usually deciduous, tan or brown, cylindric to funnelform, 1–6 mm, margins oblique, face not fringed with reflexed hairs and slender bristles at base, otherwise glabrous or scabrid;
petiole 0.5–10 cm, glabrous or scabrid in lines;
blade cordate, truncate-deltate, or hastate, 2–14 × 2–7 cm, base cordate, margins wavy, scabrid, apex acuminate, abaxially and adaxially faces glabrous or papillose to scabrid, not glaucous, the abaxial rarely minutely dotted.
axillary, erect or spreading, spikelike, 2–10(–15) cm, axes puberulent;
peduncle 0.1–10 cm or absent, glabrous or scabrid distally in lines.
axillary, erect or spreading, racemelike, 1–28 cm, axes scabrid;
peduncle 0.1–7 cm or absent, scabrid.
ascending or spreading, articulated distally, 1–3 mm, glabrous or, rarely, scabrid.
ascending or spreading to reflexed, articulated distally, 4–8 mm, glabrous.
bisexual, 3–6 per ocreate fascicle;
perianth nonaccrescent, greenish white, often with pinkish or purplish base, 3–5 mm including stipelike base, glabrous or outer 3 with blunt, hyaline hairs;
tepals elliptic to obovate, apex obtuse to acute, outer 3 obscurely keeled;
stamens 8;
filaments flattened proximally, glabrous;
styles connate distally;
stigmas capitate.
bisexual, 3–6 per ocreate fascicle;
perianth accrescent in fruit, green to white or pinkish, 3.8–8 mm including stipelike base, glabrous;
tepals elliptic to obovate, apex obtuse to acute, outer 3 winged;
stamens 8;
filaments flattened proximally, pubescent proximally;
styles connate;
stigmas capitate.
included, black, 4–5(–6) × 1.8–2.3 mm, dull, minutely granular-tuberculate, especially on faces; fruiting perianth glabrous or with blunt, hyaline hairs, wings absent or, rarely, flat to undulate, 0.4–0.9 mm wide at maturity, scarcely decurrent on stipelike base, margins entire.
included, dark brown to black, 2–6 × 1.4–3.5 mm, shiny, smooth; fruiting perianth glabrous, wings undulate or crinkled, rarely flat, (0.7–)1.5–2.1 mm wide, decurrent on stipelike base nearly to articulation, margins wavy-crenate to incised or lacerate, rarely entire.
= 40.
= 20.
Fallopia convolvulus
Fallopia scandens
Fallopia convolvulus can be an aggressive weed in crop fields. Rare plants with winged fruiting perianths have been named var. subalata; that characteristic often varies within populations.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Fallopia scandens has a complex nomenclatural history, which in North America usually involves three taxonomic elements: F. scandens and F. cristata, both native in North America, and F. dumetorum, which is native in Europe. Achene and perianth characters have been used to distinguish these elements, but variable and intergrading morphologies have caused taxonomists to combine them variously. Morphometric (S. T. Kim et al. 2000) and flavonoid (M. H. Kim et al. 2000) studies suggest that F. scandens and F. dumetorum are distinct species. Where F. scandens is absent, European specimens of F. dumetorum are distinctive. This distinction is far less clear in North America, where both species occur. Experience suggests that many North American herbarium specimens attributed to F. dumetorum are misidentified.
Fallopia cristata has been distinguished from F. scandens and F. dumetorum by its smaller fruiting perianths (5–7[–9] mm) bearing narrower (1.2–1.7 mm wide), undulate-crenate or lacerate wings, and smaller achenes (2.1–2.7 mm). Extreme forms are easily identified; some specimens grade gradually into F. scandens, making recognition of F. cristata of questionable utility. S. T. Kim et al. (2000) used morphometric studies as a basis for recommending that F. cristata is best treated as a variety of F. scandens.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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